Magnetic brake controller



E. E. HEWITT Feb. 28, 1939.

MAGNETIC BRAKE CONTROLLER 1956 4 Sheets-Sheet 1 Filed Oct. 16

INVENTOR ELLIS E. HEWITT ATTORNEY Feb. 28, 1939. E E HEWITT MAGNETIC BRAKE CONTROLLER Filed Oct. 16, 1936 4 SheetsSheet 2 1v 3 m 4% w l o 9 .g Q a I #11 1 N@\ 5 N 2 m a Nw 2 6 l V mm 2 9 m om 0 R 12R m @m N m@ m ,7 Q .1 WW I 4 n O o@ 15; a; m l 1 E 3 I HW 5 IE I, q 5 I y I LNIMMI/ d w 3 w v M p E k 1 a 5 m; B: w 1 y U 6 FY E. E. HEWITT MAGNETI C BRAKE CONTROLLER Filed Oct. 16, 1936 4 Sheets-Sheet 3 2A 5 9 0 I, 21.0! O @88 0 7 r0 ,1 W 1 1 J m f 1/ GE 6 My HR 5 m n 1 Ir) |I.. fi oo XNVENTOR ELLIS E H EWITT film/a ATTORNEY Feb. 28, 1939.

MAGNETT C BRAKE CONTROLLER -E. E4 HEWITT Filed Oct. 16, 1936 4 Sheets-Sheet '4 ELLIS E HEW] T T.

ATTORNEY Patented F eb. 28, 1939 UNITED STATES PATENT OFFICE MAGNETIC BRAKE CONTROLLER Application ()ctobcr 16, 1936, Serial No. 105,976

Claims.

This invention relates to magnetic brake controllers, and in particular to magnetic brake controllers of the fluid pressure operated type for controlling the supply of current to a magnetic track brake device or other type electric brake device.

In order to increase the flexibility of the control of magnetic track brakes, or other types of electric brakes to which current is supplied thereto, it is desirable that means be provided for graduating the supply of current in relatively fine increments. When used, magnetic track brakes are as a rule a part of a brake equipment also employing fluid pressure operated brakes. A preferred arrangement is to have the magnetic track brakes controlled in accordance with the brake cylinder pressure in the fluid pressure brake system. To accomplish this, the current supplied to the magnetic track brake devices should be graduated in as fine increments as it is possible to graduate the brake cylinder pressure.

It is a principal object of the present invention to provide an improved fluid pressure operated rheostat mechanism for controlling the supply of current to magnetic track brake devices, or other similar types of electric brake devices, in which the current supplied thereto may be varied in relatively fine increments.

A yet further object of the present invention is to provide improved fluid pressure operatet rheostat embodying an improved mechanical construction which is capable of operating efiectively over a long period without necessitating frequent repairs, which may be manufactured economa5 ically, and which is sufliciently rugged to with stand the shocks incident to installation on modern traction vehicles which operate at relatively high speeds.

Other objects of the invention will be more readily understood from the following description, which is taken in connection with the attached drawings, wherein,

Fig. 1 shows in schematic and diagrammatic form the adaptation of a rheostat device embodying the features of the present invention to a simple magnetic track brake system.

Fig. 2 is a view, partly in section, of an actual rheostat device embodying the features of the invention.

Figs. 3 to 9, inclusive, are sectional views taken along the lines 3-3, 4-4, 5-5, 6-5, 7-1, 88, and 9-9, respectively, of Fig. 2, showing various details of the rheostat device.

Referring now principally to Figs. 2 and 9, the principal parts of the improved rheostat device are an operating cylinder ID, a main operating arm II, a contact operating arm I 2, two commutator sections I3, a brush holder I4, and a calibrated balancing spring I5.

The operating cylinder ill comprises a casing having mounted therein a flexible diaphragm I'I forming with the casing a pressure tight chamber l The chamber I8 is open to a pipe I9, which pipe, as shown in Fig. 1, connects by way or a choke to a pipe ZI leading to a brake cylinder 22 forming a part of a fluid pressure brake system.

Referring again to Fig. 2, a follower 23 is disposed a jac'ent one side of the diaphragm IT and has attached thereto a stem or rod 24 terminating in an eye 25 in which is secured a roller bearing held in place by a plate 27 secured to the eye 2'5 by screws 28 (see Fig. 4) A wrist pin 29 -asses through the roller bearing 25 and thus joins or connects the rod 24 to the contact operating lever I2.

The wrist pin 29 is provided at each end with a square shaped extension 36 projecting into elongated coacting recesses or slots 3| in the main operating lever or arm ll. Both the main arm l and the contact operating arm I 2 are pivotally disposed on a pin or bolt 33 carried by two arms of a bracket 34. The bracket 34 is secured to a bed plate 35 by means of bolts 35. Where the bolt 33 passes through the main arm I I ball is arings ii are provide-d.

Integral with the contact operating arm !2 is a downwardly projecting portion 38 bearing upon a spring cup 39, below which is disposed a spring it. The spring 28 is positioned by a spring cap 4| secured to a spring housing 42 projecting downwardly from the main arm I I.

The contact operating arm 12 is provided with two lug members 45, each of which has two slotted apertures 45 therein for receiving pins 46. The two pins 45 carry intermediate the lugs 44 an insulating member l! upon which is mounted a contact plate 48, the plate being secured to the insulating member by bolts 49. A spring 58 back of the insulating member 4! acts upon it to urge it downwardly, as viewed in Figs. 2 and 5.

As particularly shown in Fig. 5, an insulating member 52 is secured to the main operating arm i l by bolts 53, and this insulating member carries two contacts 54 mounted thereon and having nuts for securing a conductor 5'! to one of the contact terminals and a conductor 58 to the other. These conductors may each pass through an insulating bushing 59 suitably mounted in apertures in the side walls of the channel shaped portion of the main operating arm II.

As will be obvious from the arrangement described, the spring 40 acting on the contact operating arm I2 maintains the contact plate 48 out of engagement with the two contacts 54, but

actuated to cause the contact plate 98 to engage the two contacts 54, the spring 59 insuring the making of a good contact, and thereafter the square extensions of the pin 29 bear upon the main operating arm I I to actuate it downwardly.

Movement of the main arm II is opposed by the calibrated balancing spring I5. This spring has one end thereof formed in the shape of a hook, as shown at 60, and this end is hooked over a pin 6| fastened in a bracket 92, which bracket is bolted to the frame by means of bolts 93. The other end of the spring I5 is curled about the shank of a bolt 64 (see Fig. 7 beneath a head 65. The bolt 94 has a portion of its shank narrowed at 66, which passes between two washers 61 placed between the side walls of the arm I I and held in place by bolt pins 68. As shown in Fig. 7, a washer 99 is disposed on the bolt 69 between two nuts I0 and the lower edges of the two centering washers 61. The centering Washers Bl are free to move on the pin bolts 68, so that a pivotal connection is formed.

In the position of the main operating arm I! shown in Fig. 2, the arm rests against a stop '52, which stop is provided with bifurcations 79 which are secured to a lug 74 by means of a pin I5. Attached to the stop I2 is a stud it which passes through an opening I? in the main operating arm, and has disposed thereon a washer l8 and two nuts 79. By suitably adjusting the two bolts l9, the swing of the arm II between the stop l2 and the washer '18 may be adjusted.

As shown in Fig. 2, the extreme right hand end of the main arm H is bifurcated to receive the brush holder I4. There is no rigid attachment between the brush holder and the main operating arm II, the bifurcations of the main arm merely pressing upon the brush holder, and sliding laterally with respect thereto so that the brush holder may move in a vertical direction while the arm is moving in an arcuate pathway.

Referring now particularly to Fig. 8, the brush holder it! comprises a casing having two ears or lugs 89 each of which has an aperture therethrough in which is disposed an insulating tube 8I. The tubes 8! are adapted to slide on rods 82 carried by bracket 83 secured to the frame 35 by bolts 84.

Within the brush holder casing are disposed two brushes 85 and 86, urged apart by a spring 81. Each brush is adapted to engage one of the commutator sections I3. The brush holder casing also has projecting therefrom two pins 99, on which is slidably disposed a contact shoe 9!) for engaging a contact bar 9! secured to a terminal board 92 by bolts 99, with a spacer of insulating material disposed therebetween.

Springs 96 disposed on the pins 89 maintain the contact shoe 99 in contact with the contact bar 9|. Leads 91 connect the contact shoe 99 with the two brushes 85 and 89.

Each of the commutator sections comprises a plurality of contact plates 99, preferably of cop per or like material, interleaved with sheets of insulation 99, such for example as mica. Both the contact plates and insulating sheets are apertured to receive insulating tubes I99, so that each commutator section may be supported on two bolts lIlI between nuts I02 from the aforementioned brackets 83.

The edge of each commutator section adjacent the brush 85 or the brush 89 is machined so that as the brush holder I4 is moved up and down, sliding on the rods 82, good contact is obtained between the brushes and the commutator contact plates.

Each of the contact plates 98 is slotted, as shown at I93, so that a cable I94 may be attached thereto, each contact plate being thus connected to a tap on a resistance mounted in a housing 98 which encloses the rheostat device, the resistance and its taps being diagrammatically indicated in Fig. 1 at 93. As is also diagrammatically indicated in Fig. l, I prefer to'connect the resistance taps to the contact plates in a manner such that as the brush holder M is moved downwardly it cuts out portions of the resistance 93 by engagement alternately with the contact plates of the two commutator sections.

The terminal board 92 is bolted to the frame 35 by means of bolts I95, and is provided with terminals 696, E91 and I98. In addition, the upper of the two bolts 94 also forms a terminal.

The terminal board, the insulating tubes, and similar insulating parts are preferably of Micarta or Bakelite, while all electrical contacting parts are preferably of copper or the like. All mechanical parts may, of course, be of steel, iron, or similar low cost material. 7

Referring now to Fig. 1, the parts of the rheostat device shown diagrammatically which correspond to the parts in the actual rheostat device are designated by like numerals. It will, of course, be understood that in the diagrammatic arrangement the details of the actual construction and mode of operation are not shown exactly. For example, the brush holder I l in the actual device, as clearly shown in Figs. 2 and 9, moves in a vertical direction, whereas it is shown as moving in an arcuate pathway in Fig. 1.

When the rheostat device is embodied in a brake system as illustrated in Fig. l, the brakes are applied by supplying fluid under pressure through the pipe 21 to the brake cylinder 22 in any of the usual ways. This supply is graduated according to the desired degree of appli cation of the brakes.

Fluid under pressure supplied to the brake cylinder 22 also flows through the choke '29 to the operating cylinder chamber. I8, resulting in moving the diaphragm il downwardly. The rod 24 is thus first actuated to rock the contact operating arm E2, to cause the contact 49 to engage the two contacts 54. If in the meanwhile the motor controller has been shifted to off position, a contact H on this controller will have engaged and bridged two stationary contacts I99, so that closing of contacts 59 will establish a circuit from a trolley H9 through a relay III, by way of conductor II2, contacts 'II and I99, conductor H9, terminal I97, conductor 51, contacts 48 and 5 5, conductor H5, terminal I98, relay Ill, and ground connection H9.

The relay III will then close its contacts II I, thus forming a circuit also from the trolley IIIl through a relay H3, this circuit comprising a conductor H9, relay contacts II'i, relay H8 and ground connection E29. The relay H8 will then close its contacts IM to establish a circuit to a magnet valve device I22, this circuit including conductor H9, contacts I2I, and conductor I23, the return connection being by way of ground conductor i24.

With current supplied to it the magnet valve device I22 will shift a double beat valve I25 therein downwardly to close communication between a supply pipe I26 (leading to a source of fluid under pressure) and the chamber of a rais- 75 ing cylinder I21, and to vent the raising cylinder to the atmosphere by way of an exhaust port I28. As the pressure in the raising cylinder I2'I diminishes the track shoe device I29 controlled thereby will drop to engagement with a track rail I30, due to gravity effect.

Closing of the contacts I2! of the relay I I8 also establishes a circuit to the track shoe device I293, which circuit beginning at the contacts PM includes conductor I23, terminal 94, conductor I32, contact bar 9i, brush holder I4, a contact plate of one of the commutator sections I3, conductor I33, all of the resistance 93, conductor I34, terminal I06, and conductor I35, the return connection being by way of ground conductor I36. The track shoe device will thus be energized to a minimum value, since all of the resistance 93 is in the circuit.

However, as fiuid pressure builds up in the rheostat chamber I8 and thus actuates the arm I I downwardly, the brush holder I4 will pass over the contact plates of the two commutator sections I3, cutting out portions of the resistance 93, as will be obvious from the connections shown in Fig. l. The movement of arm I! downwardly is opposed by the calibrated spring I5, and when the opposition exerted by this spring just balances the force due to pressure in the cylinder chamber I8, the arm I I will come to rest. When the arm thus comes to rest the current supplied to the track shoe device I29 will be proportional to the pressure of fiuid in the chamber I8.

If the pressure in chamber I8 is varied, it will be obvious that the brush holder I4 will be actuated accordingly, so that by merely varying the pressure of fluid supplied to the brake cylinder the degree of current supplied to the track shoe device may be similarly varied. When the brake cylinder pressure is reduced substantially to atmospheric pressure, spring I5 will return the arm II to the position illustrated in Fig. 1, while the spring 40 will return the contact operating arm I 2 to the position where contact 48 disengages from contacts 54. This will deenergize the relay III, resulting also in deenergization of the relay H8, and thus releasing the track shoe device.

While I have illustrated my invention with particular reference to a specific detailed design, it is not my intention to be limited to the precise details shown, or otherwise than by the spirit and scope of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a rheostat device, in combination, a commutator, a brush for movement over said commutator, a first arm for moving said brush, a contact carried by said first arm, a second arm movable with respect to said first arm, a contact car ried by said second arm, spring means urging said two arms apart whereby to maintain said two contacts out of engagement, and means including a fluid pressure operated device adapted to first actuate said second arm with respect to said first arm to cause engagement of said contacts, and to then actuate both arms to cause movement of said brush over said commutator.

2. In a rheostat device, in combination, two commutators, a brush movable over both of said commutators, a first arm for moving said brush, a contact carried by said first arm, a second arm movable with respect to said first arm, a contact carried by said second arm, spring means urging said two arms apart whereby to maintain said two contacts out of engagement, means including a fiuid pressure operated device adapted to first actuate said second arm with respect to the said first arm to cause engagement of said contacts, and to then actuate both of said arms to cause movement of said brush over both of said commutators, and resistance means connected to both of said commutators in a manner such that it is cut in or out of a circuit by alternate engagement of said brush with portions of each of said commutators.

3. In a rheostat device, in combination, a plurality of commutators, two relatively fixed guiding members disposed adjacent said commutators, a crush element insulated from and slidable alcng the length of said guiding elements, whereby said brush element is movable over said commutators, a first arm for moving said brush element, a contact carried by said first arm, a second arm movable with respect to said first arm, a contact carried by said second arm, spring means urging said two arms apart whereby to maintain said two contacts out of engagement, and means including a fiuid pressure operated device adapted to actuate said second arm with respect to said first arm to cause engagement of said contacts, and then to actuate both arms to cause movement of said brush element along said guiding elements and over said commutators.

4. In a rheostat device, in combination, two movable arms, a common pivot means for said two arms, spring means urging said two arms apart, a contact carried by one of said arms and a cooperating contact carried by the other of said arms, resistance means controlled by the movement of one of said arms, a fiuid pressure operated device for actuating said two arms, and means so constructed and arranged that upon supply of fluid under pressure to said fiuid pressure operated device one of said arms is first actuated by said device with respect to the other to cause engagement of said contacts, and then both of said arms are operated together by said device to operate said resistance means, the pressure produced by operation of said device maintaining said contacts in engagement while said two arms are operating together.

5. In a rheostat device, in combination, a first movable arm, a second arm movable with respect to and with said first arm, a contact carried by said first arm and a contact carried by said second arm, means associated with said first arm for loosely supporting the contact carried thereby and being arranged to permit uniform engagement between the engaging surfaces of said contacts when said two arms are moved toward each other, spring means acting upon one of said arms to maintain said contacts out of engagement, resistance means controlled by movement of one of said arms, and a fiuid pressure operated device connected to one of said arms, said arms being so arranged that as said device is operated the connected arm moves toward the other arm to cause engagement of said contacts and then both of said arms are operated by said device to operate said resistance means.

ELLIS E. HEWITT. 

